1. Field of the Invention
This invention relates to rotational coupling devices such as brakes and clutches and, in particular, to a rotational coupling device having an improved actuator assembly to engage the device.
2. Discussion of Related Art
Rotational coupling devices such as clutches and brakes are used to control transfer of torque between rotational bodies. When used in many industrial applications, such devices may range in diameter from several inches to several feet with torque capacities exceeding eight million pound-inches. Conventional rotational coupling devices used in industrial applications typically employ fluid (pneumatic or hydraulic) or mechanical (e.g., spring) actuators to engage and release the device to allow or prevent torque transfer. Fluid actuators in particular require a network of fluid conduits connecting to a fluid reservoir and appropriate sealing of the device. Meeting these requirements may create undesirable costs and failure and maintenance issues. Further, fluid actuators often work poorly in environments with extreme temperature conditions. Electromagnetic actuators are often used in smaller coupling devices such as those used in vehicles or consumer appliances. Such actuators have not generally found use with larger clutches used in industrial applications, however, in part because of size and packaging difficulties in scaling the actuators for use with larger clutches.
The inventors herein have recognized a need for a rotational coupling device that will minimize and/or eliminate one or more of the above-identified deficiencies.